Albumin and hemalbumin degradation by Porphyromonas gingivalis.
Degradation of bovine albumin and hemalbumin by Porphyromonas gingivalis W50 cells under non-reducing conditions at 37 degrees C was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and densitometry. Albumin and hemalbumins with heme:protein molar ratios of 1:1, 4:1 and 8:1 were degraded, yielding protease-resistant 55.6-kDa peptides. Cells of strains WPH 35, 11834 and Bg 381 also produced a similar digestion pattern. N-terminal sequencing of the 55.6-kDa albumin digestion fragment revealed two peptides with the sequences 82glu-thr-tyr-gly-asp-met-ala and 95gln-pro-glu-arg-asn-glu-cys, indicating cleavage in the N-terminal hinge region. Tosyllysylchloromethylketone and N-ethylmaleimide were the most effective in inhibiting breakdown of albumin and hemalbumin with a 1:1 heme:protein ratio. Initial degradation rates of albumin and all hemalbumins were similar, but the total amount of hemalbumins degraded over 7.5 h decreased with increased ratio of bound hemin. The specific proteolysis of hemalbumin may enable P. gingivalis to release hemin from a region of the molecule where heme binding is least avid.
Smalley
J W
JW
Department of Clinical Dental Sciences, University of Liverpool, United Kingdom.
Birss
A J
AJ
D000418:Albumins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D010450:Endopeptidases / Q000378:metabolism; D006418:Heme / Q000378:metabolism*; D016966:Porphyromonas gingivalis / Q000201:enzymology*; D011480:Protease Inhibitors / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000378:metabolism
D000418:Albumins; D011480:Protease Inhibitors; D012710:Serum Albumin, Bovine; D006418:Heme; D010450:Endopeptidases